With the arrival of the Internet of Things (IoTs) era, there is a growing requirement for systems with many sensor nodes in a variety of fields of applications. The demands for wireless, sustainable ...and independent operation are becoming more and more important for large‐scale sensor networks and systems. For these purposes, a self‐powered sensory system that can utilize the self‐harvested energy from its surroundings to drive the sensors and directly sense external stimuli has attracted great attention. The invention and rapid development of piezoelectric generators (PENGs), which take Maxwell's displacement current as the driving force, has been pushing forward research on self‐powered active mechanical sensors, electronic skins, and human‐robotic interaction. Here, this review starts with a brief introduction of piezoelectric materials, fabrication, and performance improvement. Then, the energy harvesters used for self‐power systems based on recent progress are reviewed. After that, PENGs applications toward recent self‐powered active sensors are divided into four aspects and highlighted, respectively. Moreover, some challenges and future directions for the self‐powered multifunctional sensors are put forward. It is believed that through the continuous investigations into PENG‐based self‐powered active sensors, they will soon be used in touch screens, electronic skins, health care, environmental monitoring, and intelligence systems.
This review paper delivers a comprehensive discussion on the recent development of piezoelectric nanogenerators, covering the typical piezoelectric materials, fabrication process, strategies for the enhancement of piezoelectric performance, self‐powered sensors for multifunctional applications, and artificial intelligence. Future challenges and potential research directions for the self‐powered multifunctional sensors are also involved.
The dependence of refractive index on the concentration and temperature in six kinds of aqueous solutions was investigated. The six solutions were three electrolyte solutions (NaCl, KCl, and CaCl2), ...a polar solution (glucose solution), a nonpolar solution (ethyl acetate solution), and a protein solution (bovine serum albumin solution). It was found that dn/dc decreased with temperature and dn/dT decreased with concentration in polar, nonpolar, and electrolyte solutions. While in protein solution, both of the derivatives showed an opposite behavior due to the thermal aggregation effect of proteins. According to the experimental results, the empirical expressions of the refractive indices in terms of both concentration and temperature were derived for the six solutions. By having the derivatives of refractive index n with respect to concentration c (dn/dc) and with respect to temperature T (dn/dT) respectively from the expressions, the dependence of (dn/dc) on temperature and that of (dn/dT) on concentration were obtained.
We report a smart phone based handheld wireless spirometer which uses a Lilly type sensing flowhead for respiratory signal acquisition and transmits the data to smartphone or other mobile terminals ...with Bluetooth signal transmission for data processing and result display. The developed spirometer was demonstrated to be able to detect flow rates ranging from 0-15 L/s with an accuracy of 4 mL/s, and can perform tests of flow volume (FV), forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow (PEF), etc. By having the functions and precision comparable to laboratory spirometers, it satisfies the American Thoracic Society and European Respiratory Society (ATS/ERS) proposed performance requirements for spirometer. At the same time, it is low cost, light and handy, low power consumption battery-powered. The test of 12 cases of subjects using the developed spirometer also indicated that it was easy to use for both providers and patients, and suitable for the Point of Care Test (POCT) of chronic obstructive pulmonary disease (COPD) and asthma at general-practice settings and homes.
The development of massive open online courses (MOOCs) has launched an era of large-scale interactive participation in education. While massive open enrolment and the advances of learning technology ...are creating exciting potentials for lifelong learning in formal and informal ways, the implementation of efficient and effective assessment is still problematic. To ensure that genuine learning occurs, both assessments for learning (formative assessments), which evaluate students' current progress, and assessments of learning (summative assessments), which record students' cumulative progress, are needed. Providers' more recent shift towards the granting of certificates and digital badges for course accomplishments also indicates the need for proper, secure and accurate assessment results to ensure accountability. This article examines possible assessment approaches that fit open online education from formative and summative assessment perspectives. The authors discuss the importance of, and challenges to, implementing assessments of MOOC learners' progress for both purposes. Various formative and summative assessment approaches are then identified. The authors examine and analyse their respective advantages and disadvantages. They conclude that peer assessment is quite possibly the only universally applicable approach in massive open online education. They discuss the promises, practical and technical challenges, current developments in and recommendations for implementing peer assessment. They also suggest some possible future research directions. (HRK / Abstract übernommen).
Energy-efficient intelligent systems incorporating modern electronics, circuits, and power sources have rapidly become inseparable for a wide range of applications. Here, we propose a prototype of ...energy autonomous functional paper modules, which comprise triboelectric energy harvester, power management circuits (PMCs), energy storage units, and back-end functional circuits. Each of the paper modules has its specific function and can be used individually, incorporated, or replaced/selected depending on different circumstances. The fabricated paper modules are ready to convert mechanical energy into electricity through the paper-based triboelectric nanogenerator (paper-TENG) unit; the converted AC output can be delivered to the PMC paper module and regulated into DC output to improve the charging efficiency for energy storage units; the stored electrochemical energy can be successfully used to drive the back-end module of functional circuits (including flowing LEDs, temperature/humidity sensors, and wireless transmitters). The working process of the sustainable paper modules implies an energy circulation of mechanical energy conversion, electrochemical energy storage, and energy utilization in functional circuits (in the form of photonic, thermal, electromagnetic, or mechanical energy). The proposed energy-autonomous functional paper modules present new paradigm for sustainable and adaptive functional circuits to extend the broader path toward efficient, economical, and customized integrative electronics and complementary self-powered systems.
A prototype of energy autonomous paper modules is proposed by integrating triboelectric energy harvester, power management circuits, energy storage units, and functional circuits, which presents new paradigm for sustainable, adaptive, and customized integrative electronics.
In this article, T800 carbon fiber/epoxy resin composite was subjected to hygrothermal aging. By analyzing the mass change, surface morphology before and after aging, infrared spectra, and dynamic ...mechanical properties, the effect of hygrothermal aging on the composite properties was studied. The hygrothermal aging of the composite after low‐velocity impact, the effects of environmental factors on the damaged area, and the post‐impact compression properties of composites were studied. The results showed that the saturation moisture absorption rate of the composite after aging (71°C constant temperature) was 0.88%. Upon increasing the impact energy, an indentation appeared before the inflection point at 35 J. When the impact energy was less than 15 J, aging did not affect invisible damage. Above this, the damaged area and number of internal cracks and defects in the composite were increased. After aging, the compressive strength of composite laminates with impact damage decreased obviously. During the aging stage, the residual compressive strength of the sample was the lowest in the moisture saturated state, and hygrothermal aging had little effect on the compression failure mode after impact.
Background/Aims: MicroRNA-21 (miR-21) has been demonstrated to play an important role in carcinogenesis; however, its mechanism of action in colorectal cancer (CRC) has not been fully elucidated. The ...aim of the present study was to explore the oncogenic function of miR-21 and its molecular mechanism in CRC. Methods: A total of 105 paired tumor and tumor-adjacent normal tissue specimens from CRC patients and two CRC cell lines (HCT-116 and SW480) were studied. The protein and mRNA expression levels of PTEN and miR-21 were examined using western blot analysis and real-time reverse transcription-PCR (qRT-PCR). Furthermore, we transfected CRC cells with different combinations of ectopic-expression vector or shRNA expression vector of miR-21 and phosphatase and tensin homolog (PTEN) to modulate the expression levels of miR-21 and PTEN respectively, and then analyzed the phenotypic alterations of CRC cells. Tumorigenesis was also evaluated by xenografting HCT-116 cells into nude mice. Results: In this study, we showed that miR-21 expression was significantly up-regulated in CRC compared to that in normal tissues. Patients with advanced Tumor-Node-Metastasis (TNM) stage, lymph node metastasis, local invasion and higher serum carcinoembryonic antigen (CEA) levels displayed significantly high expression of miR-21. The PTEN protein level in CRC tissues and cells was inversely correlated with miR-21 expression. Furthermore, the transfection of CRC cells with pre-miR-21 could inhibit apoptosis and promote cellular proliferation, invasion, cell cycle progression and growth of xenografts in nude mice, whereas the transfection of miR-21-specific shRNA resulted in the opposite phenomena. In addition, silencing or elevating PTEN protein could partially reverse the effect of miR-21-specific shRNA or pre-miR-21 on apoptosis, cell cycle distribution, and invasion of CRC cells. Moreover, over-expression or knockdown of miR-21 altered the protein expression of PTEN and phosphorylated Akt (p-AKT). Conclusion: miR-21 can modulate the malignant phenotypes such as proliferation, anti-apoptosis, cell cycle progression and invasion of CRC cells by down-regulating PTEN protein expression. The results of study might improve our understanding of the regulatory mechanism of miR-21 and provide useful targets and approaches for the clinical diagnosis and therapy of CRC.
We aimed to conduct psychometric tests for the Chinese version of ICECAP-A and compare the differences between ICECAP-A and EQ-5D-3L for patients with T2DM and explore the relationship between ...clinical conditions and ICECAP-A through diabetes-related clinical indicators.
Data were collected from a sample of 492 Chinese T2DM patients. The reliability and validity of the ICECAP-A were verified. Exploratory factor analysis (EFA), correlation analysis and regression analysis were conducted for both the ICECAP-A and EQ-5D-3L.
Our results show that the Chinese version of ICECAP-A has good internal consistency with an overall Cronbach's Alpha coefficient of 0.721. The mean scores of ICECAP-A and EQ-5D-3L are 0.85 vs. 0.94. A weak correlation (r = 0.116) was found between the ICECAP-A tariff and EQ-5D-3L utility. EFA showed that although the five dimensions of the ICECAP-A and EQ-5D-3L scales were loaded into two different factors respectively. However, the two scales captured different dimensions of quality of life and can complement each other. The ICECAP-A, EQ-5D-3L, and EQ-VAS scores showed differences across different socio-demographic characteristics and clinic conditions groups.
The Chinese version of the ICECAP-A capability instrument can be for assessing outcomes in adults with T2DM. It may capture more dimensions of QoL than traditional Health-related QoL (HRQoL) instruments and may be useful for economic evaluations of health care and social care for people with T2DM or other chronic diseases.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A simple and easy optical method is proposed for the determination of glass transition temperature (Tg) of polymers.
Tg was determined using the technique of microsphere imaging to monitor the ...variation of the refractive index of polymer microsphere as a function of temperature. It was demonstrated that the method can eliminate most thermal lag and has sensitivity about six fold higher than the conventional method in Tg determination. So the determined Tg is more accurate and varies less with cooling/heating rate than that obtained by conventional methods. The most attractive character of the method is that it can simultaneously determine the Tg of several polymers in a single experiment, so it can greatly save experimental time and heating energy.
The method is not only applicable for polymer microspheres, but also for the materials with arbitrary shapes. Therefore, it is expected to be broadly applied to different fundamental researches and practical applications of polymers.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Delay-tolerant networks face challenges in efficiently utilizing network resources and real-time sensing of node and message statuses due to the dynamic changes in their topology. In this paper, we ...propose a Multi-Decision Dynamic Intelligent (MDDI) routing protocol based on double Q-learning, node relationships, and message attributes to achieve efficient message transmission. In the proposed protocol, the entire network is considered a reinforcement learning environment, with all mobile nodes treated as intelligent agents. Each node maintains two Q-tables, which store the Q-values corresponding to when a node forwards a message to a neighboring node. These Q-values are also related to the network’s average latency and average hop count. Additionally, we introduce node relationships to further optimize route selection. Nodes are categorized into three types of relationships: friends, colleagues, and strangers, based on historical interaction information, and message forwarding counts and remaining time are incorporated into the decision-making process. This protocol comprehensively takes into account the attributes of various resources in the network, enabling the dynamic adjustment of message-forwarding decisions as the network evolves. Simulation results show that the proposed multi-decision dynamic intelligent routing protocol achieves the highest message delivery rate as well as the lowest latency and overhead in all states of the network compared with other related routing protocols for DTNs.
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